#define _CRT_SECURE_NO_WARNINGS
class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        int n = s.size();
        int hash[128] = { 0 };
        int ans = 0;
        for (int left = 0, right = 0; right < n; right++) {
            hash[s[right]]++;
            while (hash[s[right]] > 1) {
                hash[s[left]]--;
                left++;
            }
            ans = max(ans, right - left + 1);
        }
        return ans;
    }
};
